Along with the maturation of technologies related to remote electrical tilt antennas, operators are tending to use remote electrical tilt antennas. The remote electrical tilt antenna may significantly reduce cost for adjusting and maintaining an antenna downtilt, and improve working efficiency. A remote electrical tilt antenna system usually includes a smart bias-tee (Smart Bias-Tee, SBT for short), a remote control unit (Remote Control Unit, RCU for short), and an antenna supporting electrical tilting.
When a communication system has multiple remote electrical tilt antennas, RCUs of the multiple remote electrical tilt antennas are usually cascaded, so as to save SBTs. In an existing remote electrical tilt antenna system, when multiple RCUs are cascaded, they communicate with each other through a shared remote end serial communication bus such as an RS485 bus. The RS485 bus is a remote end serial communication bus in an industrial communication standard, and a CCU usually communicates with an RCU through the RS485 bus. When a center control unit (Center Control Unit, CCU for short) scans cascaded RCU links by using an XID (exchange identification) frame of a high-level data link control (High-Level Data Link Control, HDLC for short) protocol, multiple RCUs may respond to a link scanning message simultaneously, which causes bus conflict. Therefore, problems, such as link scanning failure, scanning incompletion and cascade order scanning error, are highly likely to occur.
To solve the problem of the bus conflict which may exist when multiple RCUs are cascaded, scanning is performed in the prior art according to RCU sequence numbers, by using an Antenna Interface Standards Group (Antenna Interface Standards Group, ASIG for short) protocol. Therefore, a sequence number of each RCU needs to be recorded when a remote electrical tilt antenna is mounted, sequence numbers of the RCUs should be staggered as far as possible, and the sequence numbers of the RCUs are used to perform link scanning in subsequent processes, so as to solve the problem of bus conflict.
However, the inventor finds that it is difficult to control the staggering of the RCU sequence numbers. If the sequence numbers of the RCUs are recorded when a remote electrical tilt antenna is mounted, the work load of mounting the RCUs is increased, and errors may occur during the recording. Therefore, it is very difficult to solve the bus conflict in the RCU cascading by using the method according to prior art.